Raymarine · Autopilot

Raymarine ST4000 (Autohelm)

The ST4000 is Autohelm’s, later Raymarine’s, cockpit autopilot for sailing yachts: a control unit with the course computer built in, a fluxgate compass below deck and either a wheel drive clamped to the spokes or a linear tiller drive between cockpit seat and tiller. The original Autohelm ST4000 with a six-button head became the ST4000 Plus (ST4000+) with eight buttons; the April 1999 handbook still shows the black wheel drive, the 2001 handbook the grey 4000 Mk2 wheel drive, whose belt, clutch, motor and gearbox are still sold as spares. That handbook rates the wheel pilot for boats up to 8,500 kg and the tiller pilot up to 6,500 kg. The control unit is long retired, but the Mk2 wheel drive (E12093) and the tiller drive (Q047) carried on with the SmartPilot X-5 and today’s Evolution EV-100, so an upgrade can keep the existing drive.

Manuals & documents

All links go to Raymarine: its website and its own document library, hosted on Box (teledyne.app.box.com) — the ST4000 handbooks in the retired-autopilot section, the drive and spares sheets in the current one. We host no manuals or drawings.

Wear parts & part numbers

PartOEM numberAlso fitsNote
Drive beltA180831,2,3,4,5—Toothed belt for the grey 4000 Mk2 wheel drive only; it does not fit the black drive of the original ST4000 and the early ST4000 Plus. Raymarine’s fitting sheet 84104-3 comes with it; adjust the clutch after fitting.
Clutch kitA180841,6,4,7—For the grey Mk2 wheel drive: clutch eccentric, clutch roller and M5 × 30 mm screw, with Raymarine instruction sheet 84105-3. The drive has two eccentrics and two rollers (clutch side and knob side); they are the same parts.
Clutch leverA180771,4,8—Clutch lever for the grey Mk2 wheel drive, with M5 × 30 mm screw.
Adjusting knobA180781,4—Clutch ratchet knob for the grey Mk2 wheel drive, with M5 × 30 mm screw; turning it click by click sets the clutch and belt tension.
MotorA180864,9,10—Drive motor of the grey Mk2 wheel drive; the loom wires are soldered to its terminals. Not for the black drive, which has a different gear.
Gearbox (without motor)A180884,11,12—Gearbox of the grey Mk2 wheel drive.
Belt pulleyA180874,13—Machined toothed belt pulley on the gearbox shaft of the grey Mk2 wheel drive; the belt runs from it around the drive ring.
Drive ringA180764,14,15—For the grey Mk2 wheel drive: the ring the belt turns, running on the ball bearings in the bearing cage.
Ball bearings (loose balls)A180854,16,17—Bearing kit for the grey Mk2 wheel drive: 21 ball bearings and the bearing cage under the drive ring. Raymarine’s service manual shows a three-part cage; one dealer describes a five-part separator.
Seal setA180924,18—Motor loom and seal kit for the grey Mk2 wheel drive: collar nut, rubber cap, motor clamp, O-ring, loom plug assembly and gasket.
Case coverA180741,4,19—Front cover of the grey Mk2 wheel drive, supplied with a 6 mm drill bit: the holes for the spoke clamps are drilled to suit your wheel.
Case coverA180754,20,1—Back cover of the grey Mk2 wheel drive; the free slot in it is where the drive is rinsed with fresh water.
Support plateA180794—Inside the grey Mk2 wheel drive, held by two M5 × 8 mm screws (1.4 Nm); it comes off first when the belt is changed.
Spoke clampA180891,3,4,21—Single spoke clamp for the grey Mk2 wheel drive, with 12 mm and 16 mm inserts, M5 × 16 mm screws and a 3 mm Allen key. Three come with the drive; a fourth is optional on 4- and 8-spoke wheels.
Mounting bracketA180801,3,4,22—Pedestal bracket (torque restraint) for the grey Mk2 wheel drive, with four No 10 × 3/4 in screws and a 4 mm drill; its pin is cut to length on fitting.
Installation kitE150171,23,3,24—Bulkhead / box pedestal fitting kit for the grey Mk2 wheel drive on a bulkhead-mounted wheel or a box pedestal: bracket, rubber seal, metal ring and six screws; needs a 55 mm hole for the motor tube. Template and instructions 84092-1.
Power cableA180614,25—Wheel drive power cable for the grey Mk2 drive, 4.5 m, with the plug at the drive end and spade connectors at the other.
Drive unit (motor, ram)E1209326,3,4,1,27,28—Today’s Raymarine Mk II Wheel Drive with installation kit: the grey ST4000+ Mk2 drive, now rated for boats up to 7500 kg. Raymarine’s 2001 handbook also covers fitting it in place of an old black drive: cut the new bracket pin to length and reuse the pedestal holes. It is also the drive of the SmartPilot X-5 and EV-100 Wheel.
Drive unit (motor, ram)A180814,29—Grey Mk2 wheel drive unit alone: the complete drive assembly without fitting kit.
Fastening kitD11930,31,32—Attachment kit for wooden wheels, for the black wheel drive of the Autohelm 4000, the original ST4000 and the 1999 ST4000 Plus; not listed for the Mk2 drive.
Mounting bracketD13630,31—Bulkhead bracket for a wheel that is not on a pedestal, for the black wheel drive (original ST4000 and 1999 ST4000 Plus); the grey Mk2 drive uses the E15017 kit instead.
Rudder reference sensorM811051,33,3—Rudder position sensor with 10 m cable for ST4000+ wheel pilots: optional, but needed on hydraulic steering or when the steering has more than 1 % lost motion. The sensor arm must stay within ±60°; the pin on the tiller arm ideally sits 140 mm from the rudder stock (101–190 mm allowed). Installation sheet 87012-3.
Rudder reference sensorZ13130,31,34—Autohelm rudder reference transducer named in the original ST4000 wheel and tiller handbooks and in the 1999 ST4000 Plus handbook. The 2001 handbook names M81105 instead; no Raymarine document says formally that one replaces the other.
CableD1731—Extension cable for the rudder position sensor, 10 m (ST4000+).
CableD1741—Extension cable for the fluxgate compass, 10 m (ST4000+); the compass itself comes with 8 m.
Network cableD284 · D285 · D286 · D287 · D288 · D187 · D1881,30—SeaTalk cables with flat moulded plugs at both ends: D284 1 m, D285 3 m, D286 5 m, D287 9 m, D288 20 m; D187 and D188 adapt a flat plug to a male or a female round plug. The 1999 handbook gives D286 as 6 m and D187 as 0.3 m, the 2001 handbook as 5 m and 0.15 m.
Data converter / gatewayE850011—SeaTalk/NMEA interface: passes SeaTalk data on to NMEA equipment or adds a second NMEA source (ST4000+).
Drive unit (motor, ram)Q04735,1,36,37,38—Linear tiller drive of the ST4000 / ST4000+ tiller version, sold today as the Raymarine Tiller Drive. Its installation instructions 87279-3 are the tiller chapter of the ST4000+ handbook: same 620/460 mm geometry, same D001–D031 accessories. Now rated for boats up to 6000 kg (2001 handbook: 6500 kg); it is also the drive of the SmartPilot X-5 Tiller and the EV-100 Tiller.
MotorQ11437,39—Motor for the tiller drive (Q047, ST4000 tiller). Dealer sources only: one dealer lists it as a Q047 spare, a second titles it ‘ST4000T Motor’ but its text describes a wheel pilot.
End capW01438,37—Rear end cap on the housing side of the tiller drive (Q047, ST4000 tiller); one dealer source.
End capG00440,37—Plastic pushrod end that sits over the tiller pin; listed for the ST1000+, ST2000+ and ST4000 tiller drives; one dealer source.
Power socket & plugM8118141—Plug and bulkhead socket set for the tiller drive (Q047, ST4000 tiller); one dealer source.
Tiller pinD0011,34,35—Standard tiller pin for the original ST4000, the ST4000+ and today’s tiller drive: bonded with epoxy into a 6 mm hole, 25 mm deep, with its shoulder 12.5 mm above the tiller.
Mounting socketD0021,34,35—Mounting socket for the drive’s fixed end, bonded into the cockpit seat; original ST4000, ST4000+ and today’s tiller drive.
Push rod extensionD003 · D004 · D005 · D006 · D007 · D0081,34,35—Pushrod extensions, chosen by the distance from socket to tiller pin with the tiller centred (620 mm needs none): 648 mm D003 (25 mm), 673 mm D004 (51 mm), 699 mm D005 (76 mm), 724 mm D006 (102 mm), 749 mm D007 (127 mm), 775 mm D008 (152 mm). Raymarine’s tables print D007 as ‘107 mm (5 in)’; 5 in is 127 mm, which also fits the 25 mm steps.
Tiller bracketD009 · D010 · D011 · D159 · D1601,35,30—Tiller brackets that move the pin point below or above the tiller, fixed with two 6 mm bolts bonded in epoxy. Offset below / above: D009 25/51 mm, D010 51/76 mm, D011 76/102 mm, D159 102/127 mm, D160 127/152 mm. The 1999 handbook lists D012 and D013 for the two largest offsets instead of D159 and D160.
Tiller pinD014 · D020 · D0211,30,35—Special tiller pins: D014 short threaded pin 25 mm, D020 extra-length pin 72 mm, D021 extra-length threaded pin. Raymarine contradicts itself on D021: 72 mm in the 1999 and 2001 handbooks, 60 mm in the current tiller drive instructions 87279-3.
Mounting socketD026 · D027 · D028 · D029 · D0301,34,35—Pedestal sockets that raise the drive’s fixed end, chosen by dimension G in Raymarine’s table (38 mm with the standard socket): 76 mm D026, 89 mm D027, 102 mm D028, 114 mm D029, 127 mm D030; the mounting ring takes three 6 mm bolts.
Mounting socketD0311,35—Cantilever socket for a vertical cockpit side: the rod is cut to length, for offsets up to 254 mm (ST4000+ and today’s tiller drive).

Numbers checked against the sources below on 13 October 2026. Always confirm against your serial number and exact type before ordering.

Service intervals

TaskInterval
Fresh-water washAfter every trip: flush the inside of the Mk2 wheel drive with fresh water through the free slot in the back cover1
Season checkEvery season: take wheel and drive off, remove the front cover, check inside for damage, flush salt off bearings and belt with fresh water and refit; wash the case with mild detergent and rinse1
LubricationNone: the Mk2 wheel drive runs dry. Do not lubricate any part and never use mineral-based solvents such as WD-40 to clean or lubricate it. The older black drives are sealed and lubricated for life1
ClutchNo fixed interval: adjust the clutch when the belt slips in Auto or drags in Standby; renew the belt (A18083) when it is broken, frayed or stretched, or when the clutch adjustment has run out1,2
Electrical connectionsRoutinely: check that all connectors are firmly attached and free of corrosion; look for chafed or damaged cables and replace them1
CalibrationAt commissioning and whenever the heading disagrees with the steering compass: deviation correction (compass swing), then heading alignment; swing again if the average error stays above 5°1
Full serviceTiller drive: Raymarine approved service every 1000 h — a figure from the SmartPilot X-5 Tiller guide 87075-4, which uses the same drive; the ST4000 handbooks give no hours. Control unit, compass, rudder sensor and tiller drive have no user-serviceable parts: repairs by Raymarine service agents only36,1

From Raymarine’s ST4000+ owner’s handbook 81131-6 (2001), which sets checks but no schedule in hours or months. The 1000-hour tiller drive service comes from the SmartPilot X-5 Tiller guide 87075-4, the later pilot that uses the same drive.

Specifications

ModelsAutohelm ST4000 (original: six-button head, black wheel drive or tiller drive); ST4000 Plus (eight-button head; 1999 handbook, still with the black wheel drive); ST4000+ with the grey 4000 Mk2 wheel drive (2001 handbook; wheel system E12053, drive E12093). The tiller version keeps the same control unit with a linear tiller drive (today Q047)31,34,30,1,4
Years builtEarliest ST4000 Plus handbook: 81131-4 of April 1999; grey 4000 Mk2 wheel drive from 2001 (handbook 81131-6). The original Autohelm ST4000 is older; its handbooks carry no date. Retired: Raymarine files it under retired autopilots, while the Mk II wheel drive and the tiller drive are still sold30,1,42,26,35
Max boat displacementST4000+ (2001 handbook): wheel pilot 8500 kg (18700 lb), tiller pilot 6500 kg (14300 lb). Original ST4000: wheel pilot up to 8200 kg recommended and never above 9000 kg; tiller pilot up to 7000 kg. Today’s drives are rated lower: Mk II wheel drive E12093 7500 kg, tiller drive Q047 6000 kg1,31,34,26,35
Helm speed (hard over)Wheel drive 9 rpm, for steering with 1–3.5 wheel turns lock to lock; tiller drive 4.0 s lock to lock1
Voltage12 V DC nominal, 10–15 V operating range. Needs its own supply circuit: it cannot be powered from SeaTalk, but it can power SeaTalk instruments. Low voltage severely weakens the drive1
Current drawST4000+ (2001): standby 0.72 W, Auto about 10 W at 25 % duty cycle. ST4000 Plus (1999): standby 60 mA (under 200 mA with full lighting), Auto 0.5–1.5 A. Original ST4000: standby 65 mA (120 mA lit), Auto 0.7–2.5 A. All depending on trim, helm load and conditions1,30,31,34
Breaker / fuse12 A fuse or equivalent breaker in the +12 V supply (all ST4000 versions); the earlier Autohelm 4000 without SeaTalk used 15 A1,32
Power cable sizePower and tiller drive cable: up to 2.5 m 1.0 mm² (18 AWG), up to 4 m 1.5 mm² (16 AWG), up to 6 m 2.5 mm² (14 AWG). The original ST4000 asked for 1.5 mm² up to 2.5 m and 2.5 mm² up to 4 m. Supplied: 1 m power cable, 4.5 m two-core wheel drive cable1,31
Data connectionsSeaTalk in/out; NMEA 0183 input for Track and Wind Vane modes (APB, APA, RMB, XTE, BWR, BWC, VTG, RMC, VWR, MWV, VHW and others); inputs for the fluxgate compass and a rudder position sensor; motor drive output (ST4000+)1
MountingWheel drive: steering with 1–3.5 turns lock to lock and no more than 1 % lost motion (7.5° of free wheel play at two turns), otherwise fit a rudder position sensor, which hydraulic steering always needs. Mk2 drive: wheels with 3–8 spokes, three spoke clamps with 12 or 16 mm inserts (spoke measured about 135 mm from the hub); black drive: 3–6 spokes (4-spoke wheels need extra holes on the original ST4000 drive). Pedestal bracket pin 154 mm directly below the pedestal spindle, cut 10 mm longer than the gap between pedestal and drive front cover (11 mm on the black drive)1,30,31
MountingTiller drive: mounting socket to tiller pin 620 mm with the tiller centred (dimension A), rudder stock centreline to tiller pin 460 mm (dimension B); drive horizontal and at 90° to the tiller1,35
MountingFluxgate compass: supplied with 8 m cable, self-levelling to ±35° pitch and roll; on a vertical bulkhead with the cable leaving at the bottom, at least 0.8 m from the steering compass; on steel hulls at least 1.2 m above deck1
DimensionsControl unit 110 × 115 × 41 mm (90 mm panel cut-out); Mk2 wheel drive 361 mm outer diameter, 171 mm deep without spoke clamps; tiller drive 620 mm at mid-stroke, 44 mm diameter1

Good to know

  • Motor runs but the wheel does not turn? The belt is slipping, and the first fix is the clutch, not a new belt: with the clutch disengaged, loosen the knob screw two turns with a 3 mm Allen key, turn the knob four clicks clockwise, retighten and check that the wheel still turns freely with the clutch off. If the belt drags in Standby, go four clicks the other way.1
  • Fit a new A18083 belt only when the clutch adjustment has run out or the belt is frayed, cracked or stretched, and adjust the clutch again afterwards. On longer passages carry a spare belt and a clutch kit (A18084).2,1
  • Check the colour before ordering spares: the A180xx parts are for the grey 4000 Mk2 drive. The black drive of the original ST4000 and the early ST4000 Plus takes a different belt and motor and was meant to go back to a service centre when it slipped.5
  • A worn black drive can be replaced by today’s Mk II wheel drive E12093: cut the new pedestal bracket pin to length and reuse the old pedestal holes. If the ST4000 control unit fails, the same wheel drive and the Q047 tiller drive carry on with an SPX-5 or a current EV-100; our Raymarine EV-100 page lists that system’s parts.1,26,36
  • Swing the compass at under 2 knots, taking at least three minutes per full circle. If the unit then reports more than 15° deviation, or none at all, move the fluxgate: vertical bulkhead, cable down, near the boat’s pitch and roll centre, at least 0.8 m from the steering compass and away from engine, speakers and cables. Then set the heading alignment.1
  • After switch-on a wheel pilot runs to starboard for about three seconds by itself to spread belt wear; that is normal. Always reach around the wheel, never through it, to work the clutch lever.1

Fitted in

Boats whose builder lists it as standard or optional equipment:

  • Gemini 105Mc — Raymarine ST4000+ (Autohelm 4000) (Standard: Autohelm 4000 autopilot in the June 2003 specification, ‘Autohelm Autopilot 4000’ in December 2003, Raymarine ST4000+ with Mk II drive in the owner’s manual’s supplier list)
  • Catalina 36 — ST 4000 (Autohelm, option) (Factory option on the Mk II (order form of December 1995, option AI 7906 “ST 4000 Autopilot”))

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Sources

  1. teledyne.app.box.com/s/nwf2s5ha9xrltggghogu/file/3273045071
  2. teledyne.app.box.com/s/rvhycb6x1brzo64921k5tsqwv2ica3j6/file/28177310142
  3. teledyne.app.box.com/s/rvhycb6x1brzo64921k5tsqwv2ica3j6/file/92597684353
  4. navsystems.ee/wp-content/uploads/2026/05/4000serv.pdf
  5. navsystems.ee/en/product/st4000-mk2-timing-belt-a18083/
  6. teledyne.app.box.com/s/rvhycb6x1brzo64921k5tsqwv2ica3j6/file/28177322462
  7. bluebottlemarine.com/products/raymarine-st4000-mk2-clutch-kit.html
  8. bluebottlemarine.com/products/raymarine-st4000-mk2-lever-kit.html
  9. bluebottlemarine.com/products/raymarine-st4000-mk2-motor-assembly.html
  10. navsystems.ee/en/product/st4000-mk2-motor-assembly-a18086/
  11. bluebottlemarine.com/products/raymarine-st4000-mk2-gearbox-kit.html
  12. navsystems.ee/en/product/st4000-mk2-gearbox-kit-a18088/
  13. bluebottlemarine.com/products/raymarine-st4000-mk2-belt-pulley-kit.html
  14. bluebottlemarine.com/products/raymarine-st4000-mk2-drive-ring.html
  15. navsystems.ee/en/product/st4000-mk2-gears-a18076/
  16. bluebottlemarine.com/products/raymarine-st4000-mk2-bearing-kit.html
  17. navsystems.ee/en/product/st4000-mk2-bearing-kit-a18085/
  18. bluebottlemarine.com/products/raymarine-st4000-mk2-loom-and-seal-assy.html
  19. bluebottlemarine.com/products/raymarine-st4000-mk2-front-cover.html
  20. bluebottlemarine.com/products/raymarine-st4000-mk2-back-cover.html
  21. bluebottlemarine.com/products/raymarine-st4000-mk2-single-spoke-clamp.html
  22. bluebottlemarine.com/products/raymarine-st4000-mk2-torque-restraint.html
  23. teledyne.app.box.com/s/rvhycb6x1brzo64921k5tsqwv2ica3j6/file/28177254930
  24. navsystems.ee/en/product/four-wheel-drive-bulkhead-fitting-kit-e15017/
  25. bluebottlemarine.com/products/raymarine-a18061-autopilot-mk2-wheel-pilot-drive-power-cabl…
  26. raymarine.com/en-us/our-products/boat-autopilots/autopilot-drive-units/cockpit-mk-ii-whee…
  27. bluebottlemarine.com/products/raymarine-st4000-mk2-wheel-drive-inc-fitting-kit.html
  28. navsystems.ee/en/product/spares-for-ev-100-st4000-mkii-drive-only/
  29. bluebottlemarine.com/products/raymarine-st4000-mk2-wheel-drive-module.html
  30. teledyne.app.box.com/s/nwf2s5ha9xrltggghogu/file/3273057121
  31. teledyne.app.box.com/s/nwf2s5ha9xrltggghogu/file/3273060377
  32. teledyne.app.box.com/s/nwf2s5ha9xrltggghogu/file/3273021547
  33. teledyne.app.box.com/s/rvhycb6x1brzo64921k5tsqwv2ica3j6/file/22147203765
  34. teledyne.app.box.com/s/nwf2s5ha9xrltggghogu/file/3273059487
  35. teledyne.app.box.com/s/rvhycb6x1brzo64921k5tsqwv2ica3j6/file/72833730233
  36. teledyne.app.box.com/s/rvhycb6x1brzo64921k5tsqwv2ica3j6/file/32376302945
  37. navsystems.ee/en/product/pinniped-time/
  38. navsystems.ee/en/product/st4000-tiller-drive-end-cap/
  39. bluebottlemarine.com/products/raymarine-st4000t-motor.html
  40. navsystems.ee/en/product/plastic-tiller-end-cap-for-st1000-st2000-st4000/
  41. navsystems.ee/en/product/st4000-connector-and-socket/
  42. raymarine.com/en-us/download/retired-autopilots-manuals

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